diff --git a/setup.py b/setup.py
index 998360bf3..867df0320 100644
--- a/setup.py
+++ b/setup.py
@@ -105,6 +105,7 @@ setup(
         "sqlalchemy>=1.3.16, <2.0, !=1.3.21",
         "sqlalchemy-utils>=0.36.6,<0.37",
         "sqlparse==0.3.0",  # PINNED! see https://github.com/andialbrecht/sqlparse/issues/562
+        "typing-extensions>=3.7.4.3,<4",  # needed to support typing.Literal on py37
         "wtforms-json",
         "pyparsing>=2.4.7, <3.0.0",
         "holidays==0.10.3",  # PINNED! https://github.com/dr-prodigy/python-holidays/issues/406